Reactive scattering of N++H2 and deuterated analogs: Statistical calculation of cross sections and rate coefficients

Publisher Website
Google Scholar
Abstract
A dynamically biased statistical theory is used to calculate state specific cross sections for the nearly thermoneutral ion–molecule reaction N+(3PI)+H2( j)→NH++H. Conservation of parity and nuclear spin, and the anisotropy of the long‐range interaction potential are taken into account explicitly. The theory is used to calculate cross sections for all three 3PI states of the N+ ion and for rotationally excited hydrogen ( j=0–6). ln addition, the calculation has been performed for different electronic degeneracy factors (gs =1/3, 1/2, and 1), and for reaction endothermicities ΔH varying between 15 and 20 meV. The integral cross sections are used to determine numerically exact thermal rate coefficients. Comparison with published experimental results allows to determine gs and ΔH. The room‐temperature data lead to gs =1/2, while rate coefficients measured below 50 K are very sensitive to the threshold behavior and are best fitted with ΔH=17 meV. Some new experimental results, measured with a liquid nitrogen cooled RF (radio frequency) ring electrode ion trap are also included. For H2 they are in good agreement with both theory and former experiments. Some discrepancies occurring for D2 as target will be discussed.